Clamping mechanism



Sept. 22, 1959 B. E. MARTEL CLAMPING MECHANISM 4 Sheets-Sheet 1 Filed Oct. 3, 1955 illllllllllllllllllll INVENTOR flofiE-Marfel aw/1. M WWW ATTORNEYS Sept. 22, 1959 Filed Oct. 3, 1955 B. E. 'MARTEL I 2,904,869

ATTORNEYS B. E. MARTEL 2,904,869

4 Sheets-Sheet 3 CLAMPING MECHANISM Sept. 22, 1959 Filed oct. s, 1955 Sept. 22, 1959 B. E. MARTEL CLAMPING MECHANISM 4 Sheets-Sheet 4 Filed Oct. 5, 1955' 1N VENTOR fiafiZC/Varkl QJZ M W W ATTORNEYS United States Patent 9 CLAlVIPlN G MECHANISM Bob E. Martel, Dallas, Tex., assignor to Texas Instruments Incorporated, Dallas, Tex., a corporation of Delaware Application October 3, 1955, Serial No. 538,089

12 Claims. (Cl. 24-243) This invention relates to a clamping mechanism for holding flat members, and more particularly, to a clamping mechanism for holding a flexible magnetic recording disk.

There have been devised varied and sundry clamping mechanisms for planar elements, such as disks, but in almost every instance, these clamping mechanisms serve only their function of clamping and other means must be provided to obtain desired concentricity of the item clamped. Furthermore, it is characteristic of clamping mechanisms that certain parts of the mechanism must be detached in order to place or remove the items being clamped. This naturally constitutes a definite disadvantage from a time and labor standpoint as the operations of clamping and unclamping under these circumstances are time consuming.

Accordingly, it is a principal object of the present invention to provide a new and improved clamping mechanism for holding a flat member, such as a magnetic recording disk, which will automatically center the disk during the clamping operation.

It is a further object of the present invention to provide a novel clamping mechanism which allows for the easy placement and removal of the article to be held by the clamping mechanism without the necessity for detaching or even loosening any part or parts of the clamping mechanism. By means of the arrangement of the present invention it is possible to remove quickly, expediently and efficiently a disk held by the mechanism and replace it with another. In fact, the whole procedure can be carried out in a few brief seconds.

It is a still further object of the present invention to provide a novel clamping mechanism for holding a flexible magnetic recording disk which will operate more efiiciently and economically than clamping mechanisms heretofore available.

Other and further objects and advantages of the present invention will become readily apparent from the following detailed description of a preferred embodiment of the invention when taken in conjunction with the appended drawings in which:

Figure 1 is a view in section through the clamping mechanism showing it in unclamped condition;

Figure 2 is a view similar to Figurel showing the mechanism in process of clamping with spindle of the mechanism shifted to the left;

Figure 3, again, is a view similar to Figure 1 illustrating the mechanism in clamped condition;

Figure 4 is an end view of the mechanism shown in Figure 1 as viewed from the right side as indicated by line 44;

Figure 5 is a view in section taken along line 55 of Figure 1; and

Figure 6 is a schematic view illustrating how concentricity is obtained during loading.

Referring now to the drawings, there will be described a preferred embodiment of the present invention and its mode of operation.

As shown in any of Figures 1, 2 or 3, the mechanism of this invention consists of a hollow drive shaft 10 mounted in a suitable housing 11 generally indicated in the drawings by the dot-dash lines. Within the housing 11 is a motor or the like arranged to drive the hollow shaft 10. For this purpose, the hollow shaft 10 is mounted in suitable bearings (not shown).

A split-ring 13 is received in a peripheral groove cut in the outside surface of shaft 10, at a point spaced from the left end of shaft 10. Hub 14 of a clamping plate 12 sits on shaft 10 against the ring 13 so that the outer face of the clamping plate 12 is flush with the end of the shaft 10. The hub 14 is locked to the shaft 10 by means of set screw 15. A resilient neoprene ring 80 is set into the marginal peripheral edge of clamping plate 12.

Received within the shaft 10 is a spindle 16 and a rod 17, the shaft 17 being attached to one end of its spindle 16. The free end of the spindle 16 is fashioned with a conical shaped head 18 which joins with a tapered section 20. A groove 19 is defined by spindle 16 and lies between head 18 and tapered section 20.

Mounted on the right end of rod 17 is a bushing 22 with an enlarged bore at its right to define with the rod 17 an annular space. Fixed onto the rod 17 to the right of bushing 22 is a washer 23. Located on rod 17 bearing against washer 23 at one end and received in the annular space defined by bushing 22 is a spring 26. The spring 26 holds the bushing 22 in the shaft 10 to insure centering of rod 17 and to enable axial shifting of the rod 17 without wobbling. A retaining ring is fixed onto rod 17 to the right of washer 23. Further to the right, a second retaining ring 71 is fixed onto the rod 17.

Between the retaining rings are located a shift hearing 24 of the ball bearing type and a spring 25. By this arrangement, an axial thrust can be imparted to the shift bearing 24 even when the drive shaft 10 is rotating. The shift bearing 24 is mounted for relative sliding movement. The function of spring 25 is to reduce the impact on shift bearing 24 and hence, is in the nature of a shock absorber. Two pins 27 are fixed into shaft 10 and project internally. A spring 28 bearing against pins 27 on the left and bushing 22 on the right bias the spindle 16 and rod 17 to the right.

The above described assembly is adapted for sliding movement inside the sleeve 10. To the left of sleeve 10 and clamping plate 12 is located a second clamping plate 30 and its associated parts. The plate 30 is provided with a rather thick hub composed of an outer part 31 and an inner part 32. This inner part 32 is partially bored out to a diameter substantially equal to the internal diameter of shaft 10 and is arranged in registry with shaft 10 but normally spaced therefrom. The outer part 31 is provided with three equally peripherally spaced radial projections 72, as shown in Figure 5, each of which is bored out and tapped at its outer end to receive a set screw 33. A nut 73 cooperates with each set screw 33. Mounted in the inner part 32 for sliding movement in registry with the three bores are three detents 34. Positioned between each set screw and its respective detent 34 is a spring 35 which biases the detent to its innermost radial position. The clamping plate 30 and its associated elements are supported by a shaft 39 which projects through a support housing 40 adapted to be fixed to a frame for mounting the mechanism. For this purpose the supporting housing 40 is provided with flanges 41 and holes 42. The shaft 39 projects through the part 32 to its interior space and there is mounted on the end of shaft 39 a washer 43 which engages with the detents 34. A spring 44 is positioned around the shaft 39 between the washer 43 and the part 32. An enlarged washer 45 is mounted on the other end a 3 of the shaft 39 by any suitable means, such as a set screw.

An assembly comprising a'cam-driven lever, positioned at the right end of the device, is used to move the shaft 17 axially which action results in the plates 12 and being brought into clamping relation. This assembly is illustrated by any of the Figures 1, 2, or 3 together with the end view of Figure 4. A pair of yokes 46 each of which defines hook portions 47 and 48 contact the outer race of shift bearing 24 mounted on rod 17. The yokes 46 are held together by means of screws 49 and are mounted on opposite sides of a lever 50 by means of screws 51.

Lever 50 is pivotally mounted on a base 52 by means of bearing mounted stud 53. In addition, a cam assembly is mounted on a drive shaft 55 by suitable means. Drive shaft 55 is hearing mounted in base 52. One end of a spring 56 is attached to the base 52 by screw 57 while the other end of spring 56 is fastened to an anchor pin 53 disposed in the lower end of the lever 50. The spring 56 forces a cam follower roller 59 mounted on lever 50 to ride on cam surface 63 of cam 54 of the cam assembly. The cam assembly is additionally comprised of a cam follower crescent 62 which is attached to cam follower plate 61. These elements cooperate with cam surface 63 of cam 54 to form a track on which the cam follower roller 59 may ride. The cam assembly is mounted on drive shaft 55 by means of hub 60.

The operation of the clamping mechanism is as follows. in its natural, or unloaded, stage, the mechanism is as shown in Figure 1. zontal, the top of the lever 50 is to the right, and the conical head 18 of spindle 16 is flush with the outer edge of the clamping plate 12.

A recording disk 90, or similar item to be clamped, is inserted between the clamping plates 12 and 30., A pair of roller supports 75 are located spaced apart below the clamping mechanism in positions to receive and support the recording disk 90 so that the center of the disk is a short distance below the spindle centerline. This distance, for example, may be one-tenth of an inch. This feature is shown in Figure 6. The drive shaft 55 is then turned, preferably by a crank (not shown), so that the cam 54 will rotate. As the cam 54 is rotated, the cam follower roller 59 will be moved toward the right due to the eccentricity of the cam 54. This will cause the lever 50 to rotate counterclockwise about stud 53, with the yokes 46 engaging the shift bearing 24 and moving the rod 17 and the spindle 16 to the left. As the spindle 16 travels, the tapered section 20, as well as the conical head 18, will move through the hole in the center of the recording disk 90. As the spindle 16 moves through, the tapered section 20 will pick up the disk 90 and align it so that its center lies exactly along the center line of the spindle 16. In magnetic recording it is imperative that the disk be centered exactly in order that it can be replaced in the exact same position should it be removed between recording and playback. In this invention, the tapered section 20 of the spindle 16 serves to positively center every disk in an efficient and expedient manner.

As the spindle 16 moves toward the left, the conically shaped head 18 contacts the washer 43 on shaft 39 and shifts the washer 43 and the shaft 39 to the left, thus compressing the spring 44. This forces parts 31 and 32 to move toward the left until they are stopped by contact with the housing 41. During this action, the enlarged washer 45 is moved in the same direction. At the same time, the detents 34 will ride along the conical head 18 of spindle 16 and will be radially retracted compressing their associated springs 35. When spindle 16 has completed its leftward movement, the head 18 will be to the left of detents 34 and thus the springs will urge the detents 34 into the groove 19 in spindle 16. This condition is shown in Figure 2. The cam 54 has now rotated through approximately 135", the top of the lever 50 has moved to the left, as has the conical head 18 and the The 0 line of the cam 54 is horienlarged washer 45. The disk is now centered on the spindle 16, and the detents 34 now reside in groove 19 of spindle 16.

As the cam 54 continues its rotation, the eccentricity will allow the spring 56 to pull the bottom of the lever 50 to the left, causing the lever 50 to now rotate clockwise. The yokes 46 will now force the rod 17 and the spindle 16 to move toward the right. As the spindle travels, the back edge of the conical head 18 will force the detents 34 to move to the right. This, in turn will force both outer part 31 and inner part 32 to move in the same direction until the clamping plate 30 is stopped by clamping plate 12. The disk 90 will then be tightly clamped between plates 12 and 30. In this position, a peripheral marginal flange 81 on plate 30 is slightly compressing the neoprene ring 80. This enhances the clamping action. This condition of the mechanism is shown in Figure 3. The cam 54 has now rotated through approximately 225, the lever 50 is almost vertical, parts 31 and 32 have moved to the right, the detents 34 remain in groove 19, and the disk 90 is tightly held between plates 12 and 30. The pressure of head 18 against washer 43 maintains spring 44 in compression and thus both enlarged washer 45 and shaft 39 to which washer 45 is secured remain out of rubbing contact with support 40 as shaft 10 and the clamping assembly rotates.

When it is desired to remove, or tmclamp, the disk 90, the drive shaft 55 is turned until the cam 54 has rotated into its original position as shown in Figure 1. As the cam 54 rotates, the crescent 62 forces the bottom of the lever 50 to move to the left. This causes the yoke 46 to pull the rod 17 and the spindle 16 to the right. Since the clamping plate 30 is already as far right as it can go, the rightward movement of spindle head 18 will now force the detents 34 to retract radially and release from groove 19. During release, spring 25 acts as a shock absorber to reduce the impact on shift bearing 24. Since the detents 34 are no longer held in groove 19, the parts 31 and 32 will be forced to move toward the left by the spring 44. Thus the recording disk 90 is unclamped and will drop down on supports 75 and may be removed. At this time, the mechanism will have been returned to the position as shown in Figure 1, and the clamping operation may be repeated on the same disk or on another disk.

During the entire clamping and unclamping operation, the only manual functions to be performed are placing the disk between the clamping plates on the supports, turning the cam drive shaft, and removing the disk. No parts of the mechanism need be detached. No manual pressure need be applied. The operation is not long and tedious, but quick, easy and efiici'ent'. Moreover, the disk is securely held in clamped relation, and of special importance it is automatically and exactly centered during clamping.

Although the present invention has been shown and described with reference to a particular embodiment, nevertheless, various changes and modifications obvious to one skilled in the art are within the spirit, scope and contemplation of the present invention.

What is claimed is:

l. A clamping mechanism comprising a pairof clamping plates coaxially mounted for relative movement together and apart, means coaxially mounted with said clamping plates and axially slidable relative to said clamping plates, means mounted in one of said clamping plates adapted to engage with said first-mentioned means, means resiliently biasing said first-mentioned means to hold said plates in clamped relation when said second-mentioned means is engaged with said first-mentioned means and means resiliently biasing said clamping plates to their open position when said second mentioned means is disengaged with said first mentioned means.

2. A clamping mechanism as defined in claim 1 wherein said first-mentioned means is a spindle defining a conical head and a tapered section adjacent thereto adapted to cooperate with said second-mentioned means.

3. A clamping mechanism as defined in claim 2 wherein said second mentioned means includes spring loaded detents adapted to engage the conical head of said spindle.

4. A clamping mechanism comprising a pair of clamping plates coaxially mounted for relative movement together and apart, means coaxially mounted with said clamping plates and axially slidable relative to said clamping plates, means mounted in one of said clamping plates adapted to engage with said first-mentioned means, means adapted to shift said first-mentioned means into engagement with said second-mentioned means and to urge said plates into clamping relation, means resiliently biasing said first-mentioned means to hold said plates in clamped relation when said second-mentioned means is engaged with said first-mentioned means and means resiliently biasing said clamping plates to their open position when said second mentioned means is disengaged with said first mentioned means.

5. A clamping mechanism as defined in claim 4 wherein said means adapted to shift said first-mentioned means into engagement with said second-mentioned means includes a pivotally mounted yoke.

6. A clamping mechanism as defined in claim 5 wherein said means adapted to shift further includes a cam cooperating with said yoke to effect pivotal movement thereof.

7. A clamping mechanism comprising hollow shaft, a first clamping plate attached at one end of said shaft, a second plate mounted for movement toward and away from said first plate, a spindle arranged for sliding movement within said shaft, means mounted in said second clamping plate adapted to engage with said spindle, means resiliently biasing said spindle to hold said plates in clamped relation when said first-mentioned means is engaged with said spindle and means resiliently biasing said second clamping plate to open position when said first mentioned means is disengaged with said spindle to hold said plates in unclamped relation.

8. A clamping mechanism as defined in claim 7 wherein said spindle defines a conical head and a tapered section adjacent thereto.

9. A clamping mechanism as defined in claim 8 wherein said first-mentioned means includes spring loaded detents adapted to engage with the conical head of said spindle.

10. A clamping mechanism as defined in claim 7 further including shifting means for axially moving said spindle.

11. A clamping mechanism as defined in claim 10 wherein said shifting means includes a pivotally mounted yoke.

12. A clamping mechanism as defined in claim 11 wherein said shifting means further includes a cam cooperating with said yoke to effect pivotal movement thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,293,219 Rieber Aug. 18, 1942 2,302,503 Proctor Nov. 17, 1942 2,340,418 Gabel Feb. 1, 1944 

